piratechnics
Skyrockets, flares, and other glowing/exploding chemical-based fireworks dat buccaneers shoot off in an attempt to intimidate other ships into letting themselves be robbed and/or taken over by said seagoing miscreants.
Piratechnics may indeed be fear-instilling, particularly if they're especially bright or noisy; there really should be little to be frightened of, though, unless said men of fortune actually start firing live-ammunition devices like cannons or rifles.